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Astros at Mariners Prediction: Odds, expert picks, starting pitchers, betting trends and stats for July 18

It’s Friday, July 18 and the Astros (56-40) are in Seattle to take on the Mariners (51-45). Brandon Walter is slated to take the mound for Houston against Luis Castillo for Seattle.

Houston is 4-3 against Seattle this season and 3-1 in the last four, but struggled entering the All-Star break. The Astros are 1-5 over the last six games after going on a 6-1 stretch prior to that. Houston is leading the AL West by 5.0 games and has the second-easiest strength of schedule remaining.

For Seattle, they are the team 5.0 games back of Houston and are coming off a three-game sweep of Detroit that should have the Mariners feeling good, not to mention Cal Raleigh‘s home run derby title.

Let’s dive into the matchup and find a sweat or two. We’ve got all the info and analysis you need to know ahead of the game, including the latest info on how to catch first pitch, odds, recent team performance, player stats, and of course, our predictions, picks & best bets for the game from our modeling tools and staff of experts.

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Game details & how to watch Astros at Mariners

Date: Friday, July 18, 2025
Time: 10:10PM EST
Site: T-Mobile Park
City: Seattle, WA
Network/Streaming: SCHN, RSNW

Never miss a second of the action and stay up-to-date with all the latest team stats and player news. Check out our day-by-day MLB schedule page, along with detailed matchup pages that update live in-game with every out.

Odds for the Astros at the Mariners

The latest odds as of Friday:

Moneyline: Astros (+113), Mariners (-134)
Spread: Mariners -1.5
Total: 7.0 runs

Probable starting pitchers for Astros at Mariners

Pitching matchup for July 18, 2025: Brandon Walter vs. Luis Castillo
- Astros: Brandon Walter, (1-2, 3.98 ERA)
  Last outing: 6.0 Innings Pitched, 2 Earned Runs Allowed, 2 Hits Allowed, 0 Walks, and 7 Strikeouts
- Mariners: Luis Castillo, (6-5, 3.41 ERA)
  Last outing: 5.0 Innings Pitched, 3 Earned Runs Allowed, 6 Hits Allowed, 2 Walks, and 6 Strikeouts

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Expert picks & predictions for tonight’s game between the Astros and the Mariners

Rotoworld Best Bet

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Our model calculates projections around each moneyline, spread and over/under bet for every game on the MLB calendar based on data points like past performance, player matchups, ballpark information and weather forecasts.

Once the model is finished running, we put its projection next to the latest betting lines for the game to arrive at a relative confidence level for each wager.

Here are the best bets our model is projecting for Friday’s game between the Astros and the Mariners:

Moneyline: NBC Sports Bet is staying away from a play on the Astros Moneyline.
Spread: NBC Sports Bet is leaning towards a play ATS on the Houston Astros at +1.5.
Total: NBC Sports Bet is recommending a play on the over on the Game Total of 7.0.

Want even more MLB best bets and predictions from our expert staff & tools? Check out the Expert MLB Predictions page from NBC.

Top betting trends & insights to know ahead of Astros at Mariners

Houston is 4-3 versus Seattle this season
Seattle is 3-0 in the last three games
Seattle is 6-0 to the Over in the last six games
Houston is 4-2 to the Over in the last six games
Seattle is 4-1 in the last five when Castillo pitches this season
Houston is 2-5 when Walter pitches this season

If you’re looking for more key trends and stats around the spread, moneyline and total for every single game on the schedule today, check out our MLB Top Trends tool on NBC Sports!

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